Annual report pursuant to Section 13 and 15(d)

Debt - Schedule of Long-term Debt Instruments Additional Information (Details)

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Debt - Schedule of Long-term Debt Instruments Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2017
Sep. 01, 2017
Aug. 04, 2017
Jul. 27, 2017
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Jul. 31, 2017
Debt Instrument [Line Items]                
Loss on extinguishment of debt         $ 43,679,000 $ 24,229,000 $ 0  
Senior Secured Revolving Credit Facility                
Debt Instrument [Line Items]                
Credit facility, unused capacity, commitment fee percentage 0.25%              
Senior Secured Notes | 5.25% Senior Notes Due 2022                
Debt Instrument [Line Items]                
Stated interest rate 5.25% 5.25%     5.25% 5.25%    
Debt face amount $ 0 $ 400,000,000     $ 0      
Debt repurchase amount   411,433,000            
Loss on extinguishment of debt   $ 14,322,000            
Senior Notes | 4.25% Senior Notes Due 2020                
Debt Instrument [Line Items]                
Stated interest rate 4.25%     4.25% 4.25%      
Debt face amount $ 0     $ 500,000,000 $ 0      
Debt repurchase amount       509,565,000        
Loss on extinguishment of debt       $ 8,393,000        
Senior Notes | 5.75% Senior Notes Due 2021                
Debt Instrument [Line Items]                
Stated interest rate 5.75%   5.75%   5.75%      
Debt face amount $ 0   $ 600,000,000   $ 0      
Debt repurchase amount     617,538,000          
Loss on extinguishment of debt     $ 20,964,000          
Senior Notes | 3.875% Senior Notes Due 2022                
Debt Instrument [Line Items]                
Stated interest rate 3.875%       3.875%     3.875%
Debt face amount $ 1,000,000,000       $ 1,000,000,000     $ 1,000,000,000
Debt unamortized discount               $ 10,291,000
Senior Notes | 5.00% Senior Notes Due 2027                
Debt Instrument [Line Items]                
Stated interest rate 5.00%       5.00%     5.00%
Debt face amount $ 1,500,000,000       $ 1,500,000,000     $ 1,500,000,000
Debt unamortized discount               $ 16,638,000